prolonged bleeding?

Ca
On June 2nd I started birth control. I'm currently on Nexplanon, which is the implant. I started my period on the 30th & im still on it!!! That's a total of 9 days & my cycle is usually 5. I just checked & there's still blood.... I'm getting super frustrated because like every other girl, I hate being on my period. I was told that usually when girls are on this birth control periods are lighter & shorter. My period is lighter, but definitely not shorter... is my body just getting used to it? How much longer do I have to suffer? 😩😩